package com.huawei;

import java.util.Arrays;
import java.util.Scanner;

public class HJ034 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String input = scanner.nextLine();

        String[] strArr = input.split("");
        Arrays.sort(strArr);
        for (String str:strArr){
            System.out.print(str);
        }
    }
}
